Radio communication based on frequency modulation of an information signal of interest are well known in the art. To date, most such radios have been analog based. Nevertheless, some progress has been made in digitizing at least a portion of the reception, demodulation and/or audio processing functions of such a radio.
Implementation of a conventional squelch detector in such a digital radio creates a number of problems. Since the discriminator output of such a radio is sampled at audio rates, it cannot support the high-frequency (20-50 kHz) noise criterion that a conventional squelch uses for detecting channel activity. Further, the conventional squelch requires that the discriminator be operational. As a result, a digital FM radio needs to devote a substantial amount of its resources to implement a conventional squelch detector.